Femoral component for bone conservation

ABSTRACT

A femoral prosthetic component includes a patellar guide portion, a pair of condyles projecting from the guide portion and forming an intercondylar notch therebetween, a bearing surface, and an interface surface configured to face a resected surface of a femur. The interface surface comprises an anterior face and a posterior face, and is substantially contoured between the anterior and posterior face to match a contoured surface of the femur. The substantially contoured interface surface may include at least one planar surface portion to about a flat cut portion in the surface of the femur. This planar surface portion may be a distal flat at a distal face of the interface surface. The contoured interface surface may alternatively include a plurality of planar surface portions. The femoral prosthetic component is configured such that preparation of the bone to match the interface surface results in minimal resection of the distal femur.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application Ser. No.16/249,462, filed on Jan. 16, 2019, which is a continuation of U.S.application Ser. No. 14/578,007, filed on Dec. 19, 2014, which claimsthe benefit of and priority to U.S. Provisional Patent Application Ser.No. 61/921,964, filed Dec. 30, 2013, the disclosures of which are herebyincorporated herein by reference.

BACKGROUND

The present invention relates generally to orthopedic prosthesis systemsused in knee joint replacement surgeries and, more particularly, to afemoral implant for use in knee arthroplasty procedures.

The knee joint comprises the interface between the distal end of thefemur and the proximal end of the tibia. In a properly-functioning kneejoint, medial and lateral condyles of the femur pivot smoothly alongmenisci attached to respective medial and lateral condyles of the tibia.When the knee joint is damaged, the natural bones and cartilage thatform the joint may be unable to properly articulate, which can lead tojoint pain and, in some cases, interfere with normal use of the joint.

In some situations, surgery is required to restore normal use of thejoint and reduce pain. Depending upon the severity of the damage, thesurgery may involve partially or completely replacing the joint withprosthetic components. During such knee replacement procedures, asurgeon resects damaged portions of the bone and cartilage, whileattempting to leave healthy tissue intact. The surgeon then fits thehealthy tissue with artificial prosthetic components designed toreplicate the resected tissue and restore proper knee joint operation.

One knee replacement procedure—total knee arthroplasty (“TKA”)—involvesthe resection of some or all of each of the medial and lateral condylesof both the femur and tibia and the removal of the fibro-cartilagemenisci located at the femorotibial interface. A prosthetic femoralcomponent, typically made of titanium or other strong, surgical-grademetal, is fitted and secured to the distal end of the femur to replacethe resected portion of the femur. Similarly, a prosthetic tibialcomponent, the base of which is also typically made of titanium or othersuitable metal, is fitted and secured to the proximal end of the tibiato replace the resected portion of the tibia.

Femoral components commonly utilize a bone facing surface having afive-cut or five-surface baseline configuration, such as that depictedin FIGS. 1A-1C. These designs are typically not directed topatient-specific anatomy and use relatively basic lines and arcs forreduced cost manufacture. Designs of this type can be generally used onmany patients having unique knee joint anatomies, and scaled only insize to accommodate the particular patient. Though advantageous formanufacture, the five basic cut design may require a high amount of bonevolume to be removed in preparation to receive the implant thereon,thereby significantly reducing the strength of the bone.

SUMMARY

A femoral prosthetic component includes a patellar guide portion, a pairof condyles projecting from the guide portion and forming anintercondylar notch therebetween, a bearing surface, and an interfacesurface configured to face a resected surface of a femur. The interfacesurface comprises an anterior face and a posterior face, and issubstantially contoured between the anterior and posterior face to matcha contoured surface of the femur. The substantially contoured interfacesurface may include at least one planar surface portion to abut a flatcut portion in the surface of the femur. This planar surface portion maybe a distal flat at a distal face of the interface surface. Thecontoured interface surface may alternatively include a plurality ofplanar surface portions. The femoral prosthetic component may beconfigured such that preparation of the bone to match the interfacesurface results in minimal resection of the distal femur.

Another embodiment of the invention relates to a prosthetic componentincludes a prosthetic body portion, the body portion having a bearingsurface and an interface surface configured to face a resected surfaceof a bone prepared to receive the prosthetic component. The interfacesurface is substantially contoured to match a contoured surface of theprepared bone and the contoured interface surface is configured suchthat preparation of the bone to receive the prosthetic component resultsin minimal bone resection.

Yet another embodiment of the invention relates to a method forimplanting a prosthetic implant including selecting a prostheticcomponent, wherein the prosthetic component comprises a prosthetic bodyportion, the body portion having a bearing surface and an interfacesurface configured to face a resected surface of a bone prepared toreceive the prosthetic component. The method further includes removing,using a first cutting tool, a first portion of the bone to form aresected surface of the bone configured to match a counterpart portionof the interface surface of the prosthetic component. The interfacesurface of the prosthetic component is substantially contoured and isconfigured to match the resected surface of the bone that issubstantially contoured.

The invention is capable of other embodiments and of being practiced orbeing carried out in various ways. Alternative exemplary embodimentsrelate to other features and combinations of features as may begenerally recited in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 illustrates a perspective view of a post-operative prostheticknee joint fitted with a prosthetic system, consistent with an exemplaryembodiment.

FIG. 2A illustrates a top view of a first exemplary embodiment of aprosthetic component.

FIG. 2B illustrates a side view of the first exemplary embodiment of aprosthetic component.

FIG. 2C illustrates a posterior perspective view of the first exemplaryembodiment of a prosthetic component.

FIG. 3A illustrates a top view of a second exemplary embodiment of aprosthetic component.

FIG. 3B illustrates a side view of the second exemplary embodiment of aprosthetic component.

FIG. 3C illustrates a posterior perspective view of the second exemplaryembodiment of a prosthetic component.

FIG. 4A illustrates a top view of a third exemplary embodiment of aprosthetic component.

FIG. 4B illustrates a side view of the third exemplary embodiment of aprosthetic component.

FIG. 4C illustrates a posterior perspective view of the third exemplaryembodiment of a prosthetic component.

FIG. 5A illustrates a top view of a fourth exemplary embodiment of aprosthetic component.

FIG. 5B illustrates a side view of the fourth exemplary embodiment of aprosthetic component.

FIG. 5C illustrates a posterior perspective view of the fourth exemplaryembodiment of a prosthetic component.

FIG. 6 illustrates a side view of a fifth exemplary embodiment of aprosthetic component.

FIG. 7 illustrates a side view of a sixth exemplary embodiment of aprosthetic component.

FIG. 8 illustrates a side perspective view of a seventh exemplaryembodiment of a prosthetic component.

FIG. 9A illustrates a perspective view of an eighth exemplary embodimentof a prosthetic component.

FIG. 9B illustrates a top view of the eighth exemplary embodiment of aprosthetic component.

FIG. 10A illustrates a perspective view of a ninth exemplary embodimentof a prosthetic component.

FIG. 10B illustrates a top view of the ninth exemplary embodiment of aprosthetic component.

FIG. 11A illustrates a perspective view of a tenth exemplary embodimentof a prosthetic component.

FIG. 11B illustrates a top view of the tenth exemplary embodiment of aprosthetic component.

FIG. 12A illustrates a front perspective view of an eleventh exemplaryembodiment of a prosthetic component.

FIG. 12B illustrates a rear perspective view of the eleventh exemplaryembodiment of a prosthetic component.

FIG. 13A illustrates a front perspective view of a twelfth exemplaryembodiment of a prosthetic component.

FIG. 13B illustrates a rear perspective view of the twelfth exemplaryembodiment of a prosthetic component.

FIG. 14A illustrates a front perspective view of a thirteenth exemplaryembodiment of a prosthetic component.

FIG. 14B illustrates a rear perspective view of the thirteenth exemplaryembodiment of a prosthetic component.

FIG. 15 illustrates a rear view of a fourteenth exemplary embodiment ofa prosthetic component.

FIG. 16 illustrates a side view of a prosthetic component according toan exemplary embodiment having a first embodiment of an elongatedprojection.

FIG. 17 illustrates a side view of a prosthetic component according toan exemplary embodiment having a second embodiment of an elongatedprojection.

FIG. 18 illustrates a side view of a prosthetic component according toan exemplary embodiment having a third embodiment of an elongatedprojection.

FIG. 19A illustrates a side view of a first embodiment of a trialprojection.

FIG. 19B illustrates a top view of the first embodiment of a trialprojection.

FIG. 20A illustrates a side view of a second embodiment of a trialprojection.

FIG. 20B illustrates a top view of the second embodiment of a trialprojection.

FIG. 21A illustrates a side view of a third embodiment of a trialprojection.

FIG. 21B illustrates a top view of the third embodiment of a trialprojection.

FIG. 22A illustrates a side view of a fourth embodiment of a trialprojection.

FIG. 22B illustrates a top view of the fourth embodiment of a trialprojection.

FIG. 23A illustrates a side view of a fifth embodiment of a trialprojection.

FIG. 23B illustrates a top view of the fifth embodiment of a trialprojection.

FIG. 24A illustrates a side view of a sixth embodiment of a trialprojection.

FIG. 24B illustrates a top view of the sixth embodiment of a trialprojection.

FIG. 25A illustrates a rear view of a fifteenth exemplary embodiment ofa prosthetic component.

FIG. 25B illustrates a front perspective view of the fifteenth exemplaryembodiment of a prosthetic component.

FIG. 25C illustrates a top view of the fifteenth exemplary embodiment ofa prosthetic component.

FIG. 26A illustrates a front perspective view of a sixteenth exemplaryembodiment of a prosthetic component.

FIG. 26B illustrates a top view of the sixteenth exemplary embodiment ofa prosthetic component.

FIG. 27A illustrates a perspective view of a distal femur prepared toreceive a femoral component according to an exemplary embodiment.

FIG. 27B illustrates a perspective view of a distal femur having anexemplary femoral component attached thereto.

FIG. 28 illustrates a perspective view of an embodiment of a surgicalsystem according to an exemplary embodiment.

FIG. 29 illustrates a block diagram of a model surgical system accordingto an exemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the application isnot limited to the details or methodology set forth in the descriptionor illustrated in the figures. It should also be understood that theterminology is for the purpose of description only and should not beregarded as limiting.

FIG. 1 illustrates a prosthetic implant system 110 implanted on apatient's knee. The prosthetic implant system 110 shown comprises aplurality of components, each of which is configured to replace arespective resected portion of the native knee joint. According to oneembodiment, prosthetic implant system 110 may include a tibial implantsystem 120 and a femoral component 130. After installation during kneereplacement surgery, tibial implant system 120 and femoral component 130cooperate to replicate the form and function of a native knee joint.

Femoral component 130 may be secured to the distal end of femur 102 andconfigured to replace the structure and function of the native femoralportion of the knee joint 100. As such, femoral component 130 may bemanufactured from surgical-grade metal or metal alloy material (such assurgical-grade steel, titanium, cobalt-chrome, etc.) that issubstantially rigid for providing sufficient strength to support theforces required of the knee joint. According to one embodiment, femoralcomponent 130 may embody a single component having a plurality ofdifferent structural features, each configured to perform a particularfunction associated with the knee joint. For example, femoral component130 may comprise a pair of condyles 132, each of which is coupled to apatellar guide portion 133. The pair of condyles 132 may be separatedfrom one another by an intercondylar notch 138, which provides a channelthrough which one or more cruciate ligaments 103, such as anteriorcruciate ligament (ACL) 103 a and/or posterior cruciate ligament (PCL)103 b, may pass.

Femoral component 130 may be configured to engage and articulate withportions of tibial implant system 120, as shown in FIG. 1 . During use,the femur is rotated relative to the tibia during flexion and extension,which causes femoral component 130 depicted in FIG. 1 to rotate relativeto a base portion 121 across the top surface of insert portions 123.

Referring particularly to FIGS. 2A-2C (and similarly shown in theembodiments of FIGS. 3A-26 ), the body portion of femoral component 230comprises a patellar guide portion 233 and a pair of condyles 232,including a medial condyle 232 a and lateral condyle 232 b. Patellarguide portion 233 of femoral component 230 may extend from the front ofthe distal end of the femur and curve downward toward the intercondylarfossa of the femur, which is exposed by intercondylar notch 238. Medialand lateral condyles 232 a, 232 b project from the bottom of patellarguide portion 233 and extend on either side of intercondylar notch 238,around the underside of the femur and continuing toward the posterior ofthe femur.

The body portion of femoral component 230 also includes a bearingsurface 235 a and an interface surface 235 b. Bearing surface 235 acomprises a curved, outward-facing (inferior) surface formed by patellarguide portion 233 and condyles 232. Accordingly, bearing surface 235 ais configured to articulate with one or more features of the knee joint,such as the patella (not shown). Interface surface 235 b comprises theinner (superior) surface of femoral component 230 and is configured toengage with and attach to the resected surface of femur 102. Theabove-noted characteristics of femoral component 230 may be included,alone or in combination, as part of each of the exemplary embodimentsdiscussed herein, though specific reference to these features in eachembodiment may not be made.

According to the embodiment of FIGS. 2A-2C, interface surface 235 b mayinclude a plurality of planar surfaces, each of which corresponds to aresected plane of the femur that has been prepared using a cutting toolhaving a planar cutting blade. The planar surfaces of the interfacesurface 235 b of femoral component 230 are configured to match with ananterior cut, an anterior chamfer cut, a distal cut, a posterior chamfercut, and a posterior cut. Although illustrated as having five planarsurfaces in the baseline embodiment of FIGS. 2A-2C, it is contemplatedthat interface surface 235 b may be configured as having any shapesuitable for engagement with a resected surface of the femur.

Indeed, with increasing use and capabilities of computer-assistedsurgery (CAS) systems (such as that depicted in FIG. 28 and discussedbelow), a user may have the freedom to perform a greater variety ofcuts, using a variety of tools to prepare the resected surface of thebone. Advantageously, with the ability to make these cuts moreefficiently and with greater ease, prosthetic components, and interfacesurfaces in particular, may be configured in such a way that minimizesthe amount of bone that must be resected to prepare the bone, such asthe distal end of the femur, to receive the prosthetic component. Otheradvantages of enhanced interface surface designs include better fixationof the implant on the bone, thinner implants, shorter operating roomtime, and minimizing stresses and strains on the bone, implant, andfixation cement. Finally, enhanced component designs (made possible bythe advances in CAS technology and systems) may allow for tailoring thecomponent to patient-specific anatomy, which can similarly provide theadvantages noted above and can result in greater longevity of thecomponent. FIGS. 3A-12 show various exemplary embodiments exhibiting thecomponent variations to minimize resected bone and provide at least theadvantages described above.

Referring to FIGS. 3A-3C, femoral component 330 has a multi-planarinterface surface 335 b. In the embodiment shown, the interface surface335 b has eight planar surfaces, though any number of planar surfacesmay be used. The planar faces include, at least, an anterior face 341,distal face 343, and posterior face 345. Distal face 343 includes distalface portion 343 a at least partially on medial condyle 332 a and distalface portion 343 b at least partially on lateral condyle 332 b.Similarly, posterior face 345 includes posterior face portion 345 a atleast partially on medial condyle 332 a and posterior face portion 345 bat least partially on lateral condyle 332 b. As the number of planarsurfaces of the interface surface 335 b increases, the more closely theinterface surface 335 b resembles a fully contoured surface betweenanterior face 341 and posterior face 345. Preparing a bone to receive aprosthetic component having a contoured interface surface 335 b allowsfor the greatest amount of bone to be conserved. Conversely, largerstraight cuts require a greater amount of bone to be resected. Theembodiment of FIGS. 3A-3C, having several planar surfaces on itsinterface surface 335 b, requires less bone removal than, for example,the embodiment shown in FIGS. 2A-2C. While nearly resembling a contouredinterface surface 335 b and thus providing improved bone conservation,the multi-planar configuration also allows for use of a single toolthroughout the preparation process (such as a tool having a planarblade, i.e. straight cut sagittal saw), and is intended to reduceoperating room time over configurations that may require changingbetween tools (for example, to a rotary cutting tool) during theprocedure.

FIGS. 4A-4C depict an embodiment of a femoral component 430 having afully contoured interface surface 435 b between anterior face 441 andposterior face 445. A fully contoured configuration is a preferredconfiguration for maximum bone conservation. A prepared contouredsurface of the distal femur 102, made possible by using a rotary cuttingtool, such as a burr, rather than a sagittal saw for at least some cuts,requires the removal of less bone from the femur 102. A fully contouredinterface surface 435 b can also advantageously produce a relativelythin implant compared with the profile of the embodiments of FIGS. 2A-2Cand 3A-3C.

FIGS. 5A-5C depict a femoral component 530 having an interface surface535 b with a hybrid configuration. Femoral component 530 has an anteriorface 541 and posterior face 545 separated by a contoured surface with adistal flat portion 543, having a first distal flat 543 a and a seconddistal flat 543 b. The configuration of the interface surface 535 b is apreferred embodiment for its bone conservation advantages (by way of thesubstantially curved surface between anterior face 541 and posteriorface 545), but as an advantage over the fully contoured configuration ofFIGS. 4A-4C, the hybrid configuration of femoral component 530 may alsobe preferred by surgeons accustomed to flat planar surfaces to aide inpositioning and orientation with confidence. Bone preparation to receivefemoral component 530 utilizes both a rotary cutter and a straight cutsagittal saw to shape the bone to match interface surface 535 b. Otherfeatures of the embodiment of FIGS. 5A-5C, such as the median groove 533a, canopy 550, and elongated projections 534 will be discussed ingreater detail below.

Other exemplary femoral components are shown in FIGS. 6-8 . Theseexemplary embodiments depict various ways in which femoral components,particularly the interface surface of femoral components, can bemodified in order for bone conservation, better patient-specific fit,thinner implant profile, and other component enhancements. As shown inFIG. 6 , femoral component 630 has an anterior face 641, distal face643, and posterior face 645. In the embodiment shown, distal face isangled distally from anterior face 641 towards posterior face 645.Femoral component 730 shown in FIG. 7 also includes an anterior face741, distal face 743, and posterior face 745. In this embodiment,between each of the planar cut segments at the faces 741, 743, and 745is a non-planar surface segment such as cylindrical chamfer cuts 742 and744. Cylindrical chamfer cuts 742, 744 provide a smooth, curvedtransition between the faces 741, 743, 745 of interface surface 735 b,which as noted above, lessens the amount of bone that must be removed toprepare the bone to receive the implant. Any combination of planarsegments and non-planar surface segments may be used in an embodimentsimilar to provide a substantially contoured interface surface betweenanterior face 741 and posterior face 745. In the exemplary embodiment ofFIG. 8 , femoral component 830 also comprises an anterior face 841,distal face 843, and posterior face 845. In this embodiment, posteriorface 845 is pitched. This pitched surface more closely matches theanatomic configuration of the femur 102, therefore requiring less boneremoval while still maintaining a substantially uniform thickness of thecomponent 830 from the bone.

Other embodiments for conserving bone during resection and preparationto receive a femoral component include pitched planar surfaces on theinterface surfaces. The embodiments of FIGS. 9-11 depict variations ofthe five-cut femoral component 230 of FIGS. 2A-2C. FIGS. 9A-9B showfemoral component 930 having a pitched distal surface 943. As shown, twopitched planes 943 a and 943 b converge towards the center axis(extending substantially along intercondylar notch 938 and betweencondyles 932) of femoral component 930 to create the pitched distalsurface 943. The embodiment of FIGS. 10A-10B depicts femoral component1030 having a pitched distal surface 1043, as well as a pitched anteriorchamfer 1042 and posterior chamfer 1044. Femoral component 1130, shownin FIGS. 11A-11B, includes all five pitched surfaces on interfacesurface 1135 b, including pitched anterior face 1141, anterior chamfer1142, distal face 1143, posterior chamfer 1144, and posterior face 1145.

The patellar guide portion of femoral components, such as patellar guideportions 1233, 1333 and 1433 of FIGS. 12-14 , may be configured toemulate the structure and function of the native patellar surface, whichis located on the front of the distal end of femur 102. For example, asshown in FIG. 12A, patellar guide portion 1233 includes a median groove1233 a that is located toward the center of patellar guide portion 1233.Located on either side of median groove 1233 a and directly aboverespective condyles 1232 a, 1232 b are a plurality of raised surfaces1233 b, 1233 c. Median groove 1233 a provides the surface thatarticulates with the patella (or “kneecap,” not shown), while raisedsurfaces 1233 b, 1233 c prevent the patella from sliding outside ofmedian groove 1233 a. Similarly, FIGS. 13A and 14A portray median groove1333 a and 1433 a, respectively.

In accordance with the present embodiments, one feature of enhancedfemoral component structures may be femoral components having a thinnerprofile, to improve bone conservation, overall effectiveness, andpatient satisfaction in the implanted component. In order to accommodateboth the thinner profile and a deep median groove (1233 a, 1333 a, or1433 a, for example) to emulate the structure and function of the nativepatellar surface, the interface surface of the femoral component mayinclude a raised canopy portion, such as canopy 1250, 1350, 1450. Theraised canopy provides for the median groove on the bearing surface(such as bearing surfaces 1235 a, 1335 a, and 1435 a) without requiringthe patellar guide portion and portions of the medial and lateralcondyles to take on a thickness that accommodates the depth of thegroove.

The raised canopy can take on a variety of shapes and configurations. Asshown in FIG. 12B, canopy 1250 has a boxed configuration. In theembodiment of FIG. 13B, canopy 1350 takes on a v-shaped configuration.And in the embodiment shown in FIG. 14B, canopy 1450 has an archedconfiguration. The various configurations of the canopies may utilizevarious bone preparation methods and tools. The bone preparation for theboxed configuration of FIG. 12B may include a straight saw cut and tworeciprocal cuts. The bone preparation for the v-shaped configuration ofFIG. 13B may include two saw cuts in a “v” formation. The bonepreparation for the arched configuration of FIG. 14B may include a cutor cuts using a reamer. The surgical system depicted in FIGS. 28-29 maybe used to plan bone preparation and to perform the bone preparationcuts.

As discussed above with reference to FIGS. 1-2 , and now particularlyreferring to FIG. 15 , condyles 1532 may comprise medial condyle 1532 aand lateral condyle 1532 b. Condyles 1532 are configured to replace thestructure and function of the corresponding native condyles of thefemur. As such, condyles 1532 project from the lower portion of patellarguide portion 1533 on the anterior side of femur 102, curve around theunderside of femur 102, and extend to the posterior side of femur 102.Condyles 1532 are configured to provide the primary structural andarticular support for the femoral component of the knee joint. In anexemplary embodiment depicted in FIG. 15 , the posterior portion ofcondyles 1532 are curved inwardly towards a center axis of the component1530 (extending substantially along intercondylar notch 1538 and betweencondyles 1532) to more closely match the anatomic shape of the posteriorregion of the femur 102. Condyles 1532 having a curved posterior shapemay allow for a more natural feel for the patient during the range ofmotion from flexion to extension. The configuration may also providebetter contact with the tibia or a tibial component.

As shown in FIGS. 16-18 , femoral component 530 may include one or moreelongated projections 134 that protrude from the interface surface 535b. Though the elongated projections 134 are depicted on femoralcomponent 530, the elongated projections 134 discussed in this sectionmay be used in combination with any of the femoral components discussedabove. In preferred embodiments, elongated projections 134 are centeredbetween the medial and lateral edges of each condyle 532 a and 532 b.Elongated projections 134 are also preferably centeredanterior-posteriorly on the distal face 543.

Elongated projections 134 may be inserted into corresponding holes thathave been surgically formed within femur 102 during a TKA procedure. Theelongated projections 134 may be secured within the holes and configuredto limit movement between femoral component 530 and femur 102. In anexemplary embodiment, elongated projections 134 are configured to bepress fit into holes in the femur 102. Bone cement may be used tofurther secure the elongated projections 134 in the holes in the femur102. The elongated projections 134 provide increased cement bondingsurface area, and also provide stability while bonding cement is curingbetween other surfaces of the femur 102 and the femoral component.

FIGS. 16-18 depict various design combinations for the elongatedprojections 134. Elongated projections 134 may take on various forms,including by way of example, a cylinder (as in elongated projections1634, 1734), a tapered cone (as in elongated projection 1834), acruciform, or a dog bone configuration. The elongated projections 134may have a smooth (as in elongated projection 1634) or textured finish(as in elongated projections 1734, 1834), such as blasted or flutedfinish. Thin edges, such as those shown in FIGS. 17 and 18 may bite intothe bone more readily than dull edges or more rounded configurations,and therefore can provide greater stability in a press fit engagementwith the bone. At the same time, edges are preferably designed so as tonot create micro-fractures in the bone as it is advanced into the holeformed in the bone. Finally, the elongated projections 134 may havevarying tip designs, including by way of example a flat tip (as inelongated projection 1834), a tapered tip, or a round tip (as inelongated projections 1634, 1734). Though exemplary embodiments areshown in FIGS. 16-18 , any combination of various forms, finishes, andtips may be used. It is contemplated that the embodiments and featuresof elongated projections 134 may also apply to projections forstabilizing other types of prosthetic components to bone, such as forstabilizing tibial components to the proximal tibia.

FIGS. 19-24 depict various embodiments of elongated projections that maybe used with trial femoral components for confirming the size, geometry,position, and/or orientation of the selected femoral component. Thetrial projections 136 are preferably shorter than the elongatedprojections 134 so as not to disrupt the entire length of the holes inthe bone, such that elongated projections on femoral component 530 canstill achieve a press fit engagement when inserted. The trialprojections 136 may have the same or different cross-sectional shape asthe intended elongated projections 134. FIGS. 19-20 depict embodimentswherein the trial projection 136 has the same cross-sectionalconfiguration as the elongated projection 134. FIGS. 19A-19B show anembodiment having a single slot therein, while FIGS. 20A-20B depict anembodiment that is t-slotted. The slots in the trial projections 136allow for flexing of the projections as passed into the hole in thebone. FIGS. 21-22 depict embodiments having the same cross-sectionalconfiguration as the elongated projection 134, but are intended to beshifted in orientation. In this way, small amounts of bone are engagedby the trial projections 136, but not at the same location as theintended elongated projection 134, thereby allowing the elongatedprojection 134 to also engage the bone. FIGS. 22A-22B depict anembodiment that is slotted. FIGS. 23-24 depict embodiments having adifferent cross-sectional shape as the intended elongated projections134. In these figures, trial projections 136 have a triangle shape. Inthe embodiments shown, the edges of the triangle are configured to matchup with the edges of elongated projections 134. As shown in theembodiments of FIGS. 19-24 , the tip of the trial projections 136 mayalso vary, and may include flat, rounded, or tapered tip configurations.

In some embodiments, the femoral components may utilize alternativemechanisms to assist with fixation of the component to the bone. Onesuch embodiment, such as femoral component 2530 shown in FIGS. 25A-25C,does not utilize elongated projections, but rather includes one or morehalf peg extensions 2560. Half pegs 2560 may be formed in the interfacesurface 2535 b and are configured to fit into similarly shaped recessesin the prepared femur. In the embodiment shown, half pegs 2560 extendlongitudinally along the anterior face 2541 and the posterior face 2445on each of the condyles 2532. It is contemplated that half pegs 2560 mayextend laterally along the anterior face 2541 and the posterior face2545 on each of the condyles 2532, or may also be positioned on anyportion of the interface surface 2535 b between the anterior face 2541and the posterior face 2545.

FIGS. 26A-26B depict a femoral component 2630 utilizing both elongatedprojections 2634 and reinforcing keels 2670 formed in the interfacesurface 2635 b to assist with fixation of the femoral component 2630 tothe bone. In the embodiment shown, reinforcing keels 2670 a and 2670 bon the posterior face 2645 on each of the condyles 2632 extend from theposterior face 2645 towards the distal face 2643. Reinforcing keels 2670a and 2670 b are substantially centered between the medial and lateralsides of the condyles 2632, but in alternative embodiments may bepositioned in other positions or orientations. Reinforcing keel 2670 con the anterior face 2641 extends from the anterior face 2641 towardsthe distal face 2643. In the embodiment shown, reinforcing keel 2670 cis substantially centered between the medial and lateral sides of theanterior face 2641, but in alternative embodiments may be positioned inother positions or orientations.

Femur 102 may be resected to receive femoral component 2630 as shown inFIG. 27A. As shown, femur 102 has been prepared using one or more bonetools to match the configuration of interface surface 2635 b of femoralcomponent 2630. FIG. 27B shows femoral component 2630 positioned onfemur 102.

As shown in the figures, femoral components according to the presentinvention can include various combinations of the features andconfigurations as disclosed above. Though certain combinations are shownin the exemplary embodiments provided, it should be understood that anyof the disclosed femoral components, interface surfaces, elongatedprojections, trial projections, half pegs, and/or reinforcing keels maybe used in combination with one another, and such combinations arecontemplated in the present disclosure.

A method of implanting a femoral component according to the exemplaryembodiments may include selecting a prosthetic component having aprosthetic body portion including a bearing surface and an interfacesurface. The interface surface, as discussed above, is configured toface a resected surface of a bone prepared to receive the prostheticcomponent. Then, using cutting tools, portions of the bones may beremoved to form the resected surface of the bone, which is configured tomatch a counterpart portion of the interface surface of the prostheticcomponent.

The preparation of the bone, including removal of the bone, such as thedistal femur, to receive the femoral components as described herein maybe implemented using a robotic surgical system such as the RIO® RoboticArm Interactive Orthopedic System available from MAKO Surgical Corp.,Ft. Lauderdale, Fla. FIG. 28 shows an embodiment of an exemplarysurgical system 2800 in which and for which the techniques describedabove can be implemented. The surgical system 2800 includes a computingsystem 2852, a feedback mechanism such as haptic device 2854 which maycarry the surgical tool, such as a cutting tool, and a tracking system2856. In operation, the surgical system 2800 enables comprehensive,intraoperative surgical planning including planning bone preparationprocedures and performing bone preparation. The surgical system 2800 mayalso provide haptic guidance to a user (e.g., a surgeon) and/or limitsthe user's manipulation of the haptic device 2854 as the user performs asurgical procedure. The computing system 2852 may be programmed todetermine control parameters based on data representative of a patient'sanatomy (e.g., preoperative CT image data, ultrasound data); a virtual(or haptic) object associated with (or registered to) the anatomy; aparameter relative to the anatomy (e.g., a depth defined with respect toa portion of the anatomy); and/or the anatomy. The computing system 2852can control the feedback mechanism, such as haptic device 2854 togenerate a force, a torque, and/or vibration based on the position ofthe tool relative to the virtual object, the parameter, and/or theanatomy. In this way, surgical system 2800 can aid a user to plan orperform bone preparation to receive a prosthetic component according toone or more of the exemplary embodiments.

Embodiments of the subject matter, the methods, and the operationsdescribed in this specification can be implemented in digital electroniccircuitry, or in computer software embodied on a tangible medium,firmware, or hardware, including the structures disclosed in thisspecification and their structural equivalents, or in combinations ofone or more of them. In the embodiment of FIG. 28 , the computing system2852 may include hardware and software for operation and control of thesurgical system 2800. Such hardware and/or software is configured toenable the system 2800 to perform the techniques described herein. Thecomputing system 2852 includes a surgical controller 2862, a displaydevice 2864, and an input device 2866.

The surgical controller 2862 may be any known computing system but ispreferably a programmable, processor-based system. For example, thesurgical controller 2862 may include a microprocessor, a hard drive,random access memory (RAM), read only memory (ROM), input/output (I/O)circuitry, and any other known computer component. The surgicalcontroller 2862 is preferably adapted for use with various types ofstorage devices (persistent and removable), such as, for example, aportable drive, magnetic storage, solid state storage (e.g., a flashmemory card), optical storage, and/or network/Internet storage. Thesurgical controller 2862 may comprise one or more computers, including,for example, a personal computer or a workstation operating under asuitable operating system and preferably includes a graphical userinterface (GUI).

Referring to FIG. 29 , in an exemplary embodiment, the surgicalcontroller 2862 includes a processing circuit 2870 having a processor2872 and memory 2874. Processor 2872 can be implemented as a generalpurpose processor executing one or more computer programs to performactions by operating on input data and generating output. The processesand logic flows can also be performed by, and apparatus can also beimplemented as, special purpose logic circuitry, e.g., an FPGA (fieldprogrammable gate array) or an ASIC (application specific integratedcircuit), a group of processing components, or other suitable electronicprocessing components. Generally, a processor will receive instructionsand data from a read only memory or a random access memory or both.Memory 2874 (e.g., memory, memory unit, storage device, etc.) comprisesone or more devices (e.g., RAM, ROM, Flash-memory, hard disk storage,etc.) for storing data and/or computer code for completing orfacilitating the various processes described in the present application.Memory 2874 may be or include volatile memory or non-volatile memory.Memory 2874 may include database components, object code components,script components, or any other type of information structure forsupporting the various activities described in the present application.According to an exemplary embodiment, memory 2874 is communicablyconnected to processor 2872 and includes computer code for executing oneor more processes described herein. The memory 2874 may contain avariety of modules, each capable of storing data and/or computer coderelated to specific types of functions. In one embodiment, memory 2874contains several modules related to surgical procedures, such as aplanning module 2874 a, a navigation module 2874 b, a registrationmodule 2874 c, and a robotic control module 2874 d.

Alternatively or in addition, the program instructions can be encoded onan artificially generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate components or media (e.g., multiple CDs, disks, or otherstorage devices). Accordingly, the computer storage medium may betangible and non-transitory.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

Generally, a computer will also include, or be operatively coupled toreceive data from or transfer data to, or both, one or more mass storagedevices for storing data, e.g., magnetic, magneto optical disks, oroptical disks. However, a computer need not have such devices. Moreover,a computer can be embedded in another device, e.g., a mobile telephone,a personal digital assistant (PDA), a mobile audio or video player, agame console, a Global Positioning System (GPS) receiver, or a portablestorage device (e.g., a universal serial bus (USB) flash drive), to namejust a few. Devices suitable for storing computer program instructionsand data include all forms of non-volatile memory, media and memorydevices, including by way of example semiconductor memory devices, e.g.,EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internalhard disks or removable disks; magneto optical disks; and CD ROM andDVD-ROM disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an embodiment of the subjectmatter described in this specification, or any combination of one ormore such back end, middleware, or front end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), an inter-network (e.g., the Internet), andpeer-to-peer networks (e.g., ad hoc peer-to-peer networks).

Referring to the embodiment of surgical controller 2862 depicted in FIG.29 , the surgical controller 2862 further includes a communicationinterface 2876. The communication interface 2876 of the computing system2852 is coupled to a computing device (not shown) of the haptic device2854 via an interface, to the tracking system 2856 via an interface, andto the display 2864 through an interface. Through the communicationinterface 2876, pre-operative image data 2880 may also be received froman imaging system. The interfaces can include a physical interface and asoftware interface. The physical interface of the communicationinterface 2876 can be or include wired or wireless interfaces (e.g.,jacks, antennas, transmitters, receivers, transceivers, wire terminals,etc.) for conducting data communications with external sources via adirect connection or a network connection (e.g., an Internet connection,a LAN, WAN, or WLAN connection, etc.). The software interface may beresident on the surgical controller 2862, the computing device (notshown) of the haptic device 2854, and/or the tracking system 2856. Insome embodiments, the surgical controller 2862 and the computing device(not shown) are the same computing device. The software may also operateon a remote server, housed in the same building as the surgical system2800, or at an external server site.

Computer system 2852 also includes display device 2864. The displaydevice 2864 is a visual interface between the computing system 2852 andthe user. The display device 2864 is connected to the surgicalcontroller 2862 and may be any device suitable for displaying text,images, graphics, and/or other visual output. For example, the displaydevice 2864 may include a standard display screen (e.g., LCD, CRT, OLED,TFT, plasma, etc.), a touch screen, a wearable display (e.g., eyewearsuch as glasses or goggles), a projection display, a head-mounteddisplay, a holographic display, and/or any other visual output device.The display device 2864 may be disposed on or near the surgicalcontroller 2862 (e.g., on the cart as shown in FIG. 28 ) or may beremote from the surgical controller 2862 (e.g., mounted on a stand withthe tracking system 2856). The display device 2864 is preferablyadjustable so that the user can position/reposition the display device2864 as needed during a surgical procedure. For example, the displaydevice 2864 may be disposed on an adjustable arm (not shown) or to anyother location well-suited for ease of viewing by the user. As shown inFIG. 28 there may be more than one display device 2864 in the surgicalsystem 2800.

The display device 2864 may be used to display any information usefulfor a medical procedure, such as, for example, images of anatomygenerated from an image data set obtained using conventional imagingtechniques, graphical models (e.g., CAD models of implants, instruments,anatomy, etc.), graphical representations of a tracked object (e.g.,anatomy, tools, implants, etc.), constraint data (e.g., axes, articularsurfaces, etc.), representations of implant components, digital or videoimages, registration information, calibration information, patient data,user data, measurement data, software menus, selection buttons, statusinformation, and the like.

In addition to the display device 2864, the computing system 2852 mayinclude an acoustic device (not shown) for providing audible feedback tothe user. The acoustic device is connected to the surgical controller2862 and may be any known device for producing sound. For example, theacoustic device may comprise speakers and a sound card, a motherboardwith integrated audio support, and/or an external sound controller. Inoperation, the acoustic device may be adapted to convey information tothe user. For example, the surgical controller 2862 may be programmed tosignal the acoustic device to produce a sound, such as a voicesynthesized verbal indication “DONE,” to indicate that a step of asurgical procedure is complete. Similarly, the acoustic device may beused to alert the user to a sensitive condition, such as producing atone to indicate that a surgical cutting tool is nearing a criticalportion of soft tissue.

To provide for other interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving input device 2866 that enables the user to communicate with thesurgical system 2800. The input device 2866 is connected to the surgicalcontroller 2862 and may include any device enabling a user to provideinput to a computer. For example, the input device 2866 can be a knowninput device, such as a keyboard, a mouse, a trackball, a touch screen,a touch pad, voice recognition hardware, dials, switches, buttons, atrackable probe, a foot pedal, a remote control device, a scanner, acamera, a microphone, and/or a joystick. For example, input device 2866can allow the user to provide input to adjust the surgical plan. Otherkinds of devices can be used to provide for interaction with a user aswell; for example, feedback provided to the user can be any form ofsensory feedback, e.g., visual feedback, auditory feedback, or tactilefeedback; and input from the user can be received in any form, includingacoustic, speech, or tactile input. In addition, a computer can interactwith a user by sending documents to and receiving documents from adevice that is used by the user; for example, by sending web pages to aweb browser on a user's client device in response to requests receivedfrom the web browser.

The system 2800 also includes a tracking (or localizing) system 2856that is configured to determine a pose (i.e., position and orientation)of one or more objects during a surgical procedure to detect movement ofthe object(s). For example, the tracking system 2856 may include adetection device that obtains a pose of an object with respect to acoordinate frame of reference of the detection device. As the objectmoves in the coordinate frame of reference, the detection device tracksthe pose of the object to detect (or enable the surgical system 2800 todetermine) movement of the object. As a result, the computing system2852 can capture data in response to movement of the tracked object orobjects. Tracked objects may include, for example, tools/instruments,patient anatomy, implants/prosthetic devices, and components of thesurgical system 2800. Using pose data from the tracking system 2856, thesurgical system 2800 is also able to register (or map or associate)coordinates in one space to those in another to achieve spatialalignment or correspondence (e.g., using a coordinate transformationprocess as is well known). Objects in physical space may be registeredto any suitable coordinate system, such as a coordinate system beingused by a process running on the surgical controller 2862 and/or thecomputer device of the haptic device 2854. For example, utilizing posedata from the tracking system 2856, the surgical system 2800 is able toassociate the physical anatomy, such as the patient's femur, with arepresentation of the anatomy (such as an image displayed on the displaydevice 2864). Based on tracked object and registration data, thesurgical system 2800 may determine, for example, a spatial relationshipbetween the image of the anatomy and the relevant anatomy.

Registration may include any known registration technique, such as, forexample, image-to-image registration (e.g., monomodal registration whereimages of the same type or modality, such as fluoroscopic images or MRimages, are registered and/or multimodal registration where images ofdifferent types or modalities, such as MRI and CT, are registered);image-to-physical space registration (e.g., image-to-patientregistration where a digital data set of a patient's anatomy obtained byconventional imaging techniques is registered with the patient's actualanatomy); and/or combined image-to-image and image-to-physical-spaceregistration (e.g., registration of preoperative CT and MRI images to anintraoperative scene). The computing system 2852 may also include acoordinate transform process for mapping (or transforming) coordinatesin one space to those in another to achieve spatial alignment orcorrespondence. For example, the surgical system 2800 may use thecoordinate transform process to map positions of tracked objects (e.g.,patient anatomy, etc.) into a coordinate system used by a processrunning on the computer of the haptic device 2854 and/or the surgicalcontroller 2862. As is well known, the coordinate transform process mayinclude any suitable transformation technique, such as, for example,rigid-body transformation, non-rigid transformation, affinetransformation, and the like.

The tracking system 2856 may be any tracking system that enables thesurgical system 2800 to continually determine (or track) a pose of therelevant anatomy of the patient. For example, the tracking system 2856may include a non-mechanical tracking system, a mechanical trackingsystem, or any combination of non-mechanical and mechanical trackingsystems suitable for use in a surgical environment. The non-mechanicaltracking system may include an optical (or visual), magnetic, radio, oracoustic tracking system. Such systems typically include a detectiondevice adapted to locate in predefined coordinate space speciallyrecognizable trackable elements (or trackers) that are detectable by thedetection device and that are either configured to be attached to theobject to be tracked or are an inherent part of the object to betracked. For example, a trackable element may include an array ofmarkers having a unique geometric arrangement and a known geometricrelationship to the tracked object when the trackable element isattached to the tracked object. The known geometric relationship may be,for example, a predefined geometric relationship between the trackableelement and an endpoint and axis of the tracked object. Thus, thedetection device can recognize a particular tracked object, at least inpart, from the geometry of the markers (if unique), an orientation ofthe axis, and a location of the endpoint within a frame of referencededuced from positions of the markers.

The markers may include any known marker, such as, for example,extrinsic markers (or fiducials) and/or intrinsic features of thetracked object. Extrinsic markers are artificial objects that areattached to the patient (e.g., markers affixed to skin, markersimplanted in bone, stereotactic frames, etc.) and are designed to bevisible to and accurately detectable by the detection device. Intrinsicfeatures are salient and accurately locatable portions of the trackedobject that are sufficiently defined and identifiable to function asrecognizable markers (e.g., landmarks, outlines of anatomical structure,shapes, colors, or any other sufficiently recognizable visualindicator). The markers may be located using any suitable detectionmethod, such as, for example, optical, electromagnetic, radio, oracoustic methods as are well known. For example, an optical trackingsystem having a stationary stereo camera pair sensitive to infraredradiation may be used to track markers that emit infrared radiationeither actively (such as a light emitting diode or LED) or passively(such as a spherical marker with a surface that reflects infraredradiation). Similarly, a magnetic tracking system may include astationary field generator that emits a spatially varying magnetic fieldsensed by small coils integrated into the tracked object.

The haptic device 2854 may be the Tactile Guidance System™ (TGS™)manufactured by MAKO Surgical Corp., and used to prepare the surface ofthe patient's bone for insertion of the femoral component. The hapticdevice 2854 provides haptic (or tactile) guidance to guide the surgeonduring a surgical procedure. The haptic device is an interactivesurgical device, such as a robotic arm, that holds a surgical tool(e.g., a surgical burr) and is manipulated by the surgeon to perform aprocedure on the patient, such as cutting a surface of a bone inpreparation for femoral component installation. As the surgeonmanipulates the robotic arm to move the tool and sculpt the bone, thehaptic device 2854 guides the surgeon by providing force feedback thatconstrains the tool from penetrating a virtual boundary.

The construction and arrangement of the systems and methods as shown inthe various exemplary embodiments are illustrative only. Although only afew embodiments have been described in detail in this disclosure, manymodifications are possible. Accordingly, all such modifications areintended to be included within the scope of the present disclosure. Theorder or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. Other substitutions,modifications, changes, and omissions may be made in the design,operating conditions and arrangement of the exemplary embodimentswithout departing from the scope of the present disclosure.

The invention claimed is:
 1. A femoral prosthetic component, comprising:a patellar guide portion; a pair of condyles projecting from thepatellar guide portion and forming an intercondylar notch, therebetween;a bearing surface sized and configured to engage and articulate with atibial component; and a bone interface surface sized and configured toengage a resected surface of a femur, the interface surface having aposterior face, an anterior face, a distal face, a posterior chamfer,and an anterior chamfer, wherein the distal face comprises two pitchedplanes that converge with each other at an apex aligned with a centeraxis of the femoral prosthetic component to create a pitched distalsurface, the center axis extending substantially along the intercondylarnotch and between the condyles, wherein the two pitched planes pitchaway from the apex towards opposing lateral and medial edges of thefemoral prosthetic component.
 2. The femoral prosthetic component ofclaim 1, wherein the anterior chamfer and posterior chamfer are eachcomprised of two pitched planes that converge toward the center axis tocreate a pitched anterior chamfer and pitched posterior chamfer.
 3. Thefemoral prosthetic component of claim 2, wherein the anterior face andposterior face are each comprised of two pitched planes that convergetoward the center axis to create a pitched anterior face and pitchedposterior face.
 4. The femoral prosthetic component of claim 1, furthercomprising an elongated projection extending from the pitched distalsurface of the interface surface and being configured to engage a holeprepared in a femur.
 5. The femoral prosthetic component of claim 1,wherein the pitched planes slope in a direction away from the bearingsurface toward the central axis.
 6. The femoral prosthetic component ofclaim 1, wherein the anterior face and posterior face each comprise onlyone planar surface.
 7. The femoral prosthetic component of claim 1,wherein the anterior chamfer and posterior chamfer each comprise onlyone planar surface.